extensions/NV/NV_framebuffer_multisample.txt - external/github.com/KhronosGroup/OpenGL-Registry - Git at Google


            
            Name


                NV_framebuffer_multisample


            Name Strings


                GL_NV_framebuffer_multisample


            Contributors


                Contributors to EXT_framebuffer_multisample

            
                Contributors from ANGLE_framebuffer_multisample


                Gregory Roth, NVIDIA

            
                Mathias Heyer, NVIDIA

            
                Xi Chen, NVIDIA


            Contacts


                Mathias Heyer, NVIDIA (mheyer 'at' nvidia 'dot' com)


            Status


                Complete


            Version


                Last Modified Date: March 03, 2015

            
                Author Revision: #5


            Number


                OpenGL ES Extension #143


            Dependencies


                Requires OpenGL ES 2.0.


                Requires GL_NV_framebuffer_blit.


                The extension is written against the OpenGL ES 2.0.25

            
                (November 2, 2010) specification.


                OES_texture_3D affects the definition of this extension.

            
                NV_texture_array affects the definition of this extension.


                This extension interacts with OpenGL ES 3.0 and later versions.


            Overview


                This extension extends the framebuffer object framework to

            
                enable multisample rendering.


                The new operation RenderbufferStorageMultisampleNV() allocates

            
                storage for a renderbuffer object that can be used as a multisample

            
                buffer.  A multisample render buffer image differs from a

            
                single-sample render buffer image in that a multisample image has a

            
                number of SAMPLES that is greater than zero.  No method is provided

            
                for creating multisample texture images.


                All of the framebuffer-attachable images attached to a framebuffer

            
                object must have the same number of SAMPLES or else the framebuffer

            
                object is not "framebuffer complete".  If a framebuffer object with

            
                multisample attachments is "framebuffer complete", then the

            
                framebuffer object behaves as if SAMPLE_BUFFERS is one.


                A resolve operation is executed by calling

            
                BlitFramebufferNV (provided by the NV_framebuffer_blit

            
                extension) where the source is a multisample framebuffer object

            
                and the destination is a single-sample framebuffer object.

            
                Source and destination framebuffer may be either application-created

            
                or window-system provided.


            New Procedures and Functions


                void RenderbufferStorageMultisampleNV(

            
                        enum target, sizei samples,

            
                        enum internalformat,

            
                        sizei width, sizei height);


            New Tokens


                Accepted by the <pname> parameter of GetRenderbufferParameteriv:


                    RENDERBUFFER_SAMPLES_NV                     0x8CAB


                Returned by CheckFramebufferStatus:


                    FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_NV       0x8D56


                Accepted by the <pname> parameter of GetBooleanv, GetIntegerv,

            
                and GetFloatv:


                    MAX_SAMPLES_NV                              0x8D57


            Additions to Chapter 3 of the OpenGL ES 2.0 Specification (Rasterization)


                Add to the last paragraph of 3.7.2 (Alternate Texture Image Specification)

            
                (as modified by NV_framebuffer_blit) the following:


                "Calling CopyTexSubImage3DOES, CopyTexSubImage3DNV,

            
                CopyTexImage2D or CopyTexSubImage2D will result in INVALID_OPERATION

            
                being generated if the object bound to READ_FRAMEBUFFER_BINDING_NV

            
                is "framebuffer complete" and the value of SAMPLE_BUFFERS is greater

            
                than zero."


            Additions to Chapter 4 of the OpenGL ES 2.0 Specification (Per-Fragment

            
            Operations and the Framebuffer)


                Add to 4.3.1 (Reading Pixels), right before the subsection titled

            
                "Obtaining Pixels from the Framebuffer":


                "ReadPixels generates INVALID_OPERATION if READ_FRAMEBUFFER_BINDING_NV

            
                (section 4.4) is non-zero, the read framebuffer is framebuffer

            
                complete, and the value of SAMPLE_BUFFERS for the read framebuffer

            
                is greater than zero."


                In 4.3.2 (Copying Pixels), add to the section describing BlitFramebufferNV

            
                that was added by NV_framebuffer_blit.


                "If SAMPLE_BUFFERS for the read framebuffer is greater than zero and

            
                SAMPLE_BUFFERS for the draw framebuffer is zero, the samples

            
                corresponding to each pixel location in the source are converted to

            
                a single sample before being written to the destination.


                If SAMPLE_BUFFERS for the read framebuffer is zero and

            
                SAMPLE_BUFFERS for the draw framebuffer is greater than zero, the

            
                value of the source sample is replicated in each of the destination

            
                samples.


                If SAMPLE_BUFFERS for both the read and draw framebuffers are

            
                greater than zero, and the values of SAMPLES for the read and draw

            
                framebuffers are identical, the samples are copied without

            
                modification from the read framebuffer to the draw framebuffer.

            
                Otherwise, no copy is performed and an INVALID_OPERATION error is

            
                generated.


                If SAMPLE_BUFFERS for the read framebuffer is greater than zero and

            
                the format of the read and draw framebuffers are not identical, no

            
                copy is performed and an INVALID_OPERATION error is generated.


                Furthermore, if SAMPLE_BUFFERS for either the read framebuffer or

            
                draw framebuffer is greater than zero, no copy is performed and an

            
                INVALID_OPERATION error is generated if the dimensions of the source

            
                and destination rectangles provided to BlitFramebufferNV are not

            
                identical, or if the formats of the read and draw framebuffers are

            
                not identical.


                Modification to 4.4.3 (Renderbuffer Objects)


                Add, just above the definition of RenderbufferStorage:


                "The command


                    void RenderbufferStorageMultisampleNV(

            
                        enum target, sizei samples,

            
                        enum internalformat,

            
                        sizei width, sizei height);


                establishes the data storage, format, dimensions, and number of

            
                samples of a renderbuffer object's image.  <target> must be

            
                RENDERBUFFER.  <internalformat> must be one of the color-renderable,

            
                depth-renderable, or stencil-renderable formats described in table 4.5.

            
                <width> and <height> are the dimensions in pixels of the renderbuffer.  If

            
                either <width> or <height> is greater than the value of

            
                MAX_RENDERBUFFER_SIZE, or if <samples> is greater than MAX_SAMPLES_NV,

            
                then the error INVALID_VALUE is generated. If OpenGL ES is unable to

            
                create a data store of the requested size, the error OUT_OF_MEMORY

            
                is generated.


                Upon success, RenderbufferStorageMultisampleNV deletes any existing

            
                data store for the renderbuffer image and the contents of the data

            
                store after calling RenderbufferStorageMultisampleNV are undefined.

            
                RENDERBUFFER_WIDTH is set to <width>, RENDERBUFFER_HEIGHT is

            
                set to <height>, and RENDERBUFFER_INTERNAL_FORMAT is set to

            
                <internalformat>.


                If <samples> is zero, then RENDERBUFFER_SAMPLES_NV is set to zero.

            
                Otherwise <samples> represents a request for a desired minimum

            
                number of samples. Since different implementations may support

            
                different sample counts for multisampled rendering, the actual

            
                number of samples allocated for the renderbuffer image is

            
                implementation dependent.  However, the resulting value for

            
                RENDERBUFFER_SAMPLES_NV is guaranteed to be greater than or equal

            
                to <samples> and no more than the next larger sample count supported

            
                by the implementation.


                An OpenGL ES implementation may vary its allocation of internal component

            
                resolution based on any RenderbufferStorageMultisampleNV parameter (except

            
                target), but the allocation and chosen internal format must not be a

            
                function of any other state and cannot be changed once they are

            
                established. The actual resolution in bits of each component of the

            
                allocated image can be queried with GetRenderbufferParameteriv."


                Modify the definiton of RenderbufferStorage as follows:


                "The command


                    void RenderbufferStorage(enum target, enum internalformat,

            
                                                sizei width, sizei height);


                 is equivalent to calling RenderbufferStorageMultisampleNV with

            
                 <samples> equal to zero."


                In section 4.4.5 (Framebuffer Completeness) in the subsection

            
                titled "Framebuffer Completeness" add an entry to the bullet list:


                * The value of RENDERBUFFER_SAMPLES_NV is the same for all attached

            
                  images.

            
                  { FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_NV }


                Also add a paragraph to the end of the section after the definition

            
                of CheckFramebufferStatus:


                "The values of SAMPLE_BUFFERS and SAMPLES are derived from the

            
                attachments of the currently bound framebuffer object.  If the

            
                current DRAW_FRAMEBUFFER_BINDING_NV is not "framebuffer complete",

            
                then both SAMPLE_BUFFERS and SAMPLES are undefined.  Otherwise,

            
                SAMPLES is equal to the value of RENDERBUFFER_SAMPLES_NV for the

            
                attached images (which all must have the same value for

            
                RENDERBUFFER_SAMPLES_NV). Further, SAMPLE_BUFFERS is one if

            
                SAMPLES is non-zero.  Otherwise, SAMPLE_BUFFERS is zero.


            Additions to Chapter 6 of the OpenGL ES 2.0 Specification (State and State

            
            Requests)


                In section 6.1.3 (Enumeraged Queries), modify the third paragraph

            
                of the description of GetRenderbufferParameteriv as follows:


                "Upon successful return from GetRenderbufferParameteriv, if

            
                <pname> is RENDERBUFFER_WIDTH, RENDERBUFFER_HEIGHT,

            
                RENDERBUFFER_INTERNAL_FORMAT, or RENDERBUFFER_SAMPLES_NV, then <params>

            
                will contain the width in pixels, height in pixels, internal format, or

            
                number of samples, respectively, of the image of the renderbuffer

            
                currently bound to <target>."


            Dependencies on OpenGL ES 3.0 and later


                If OpenGL ES 3.0 or later is supported, the described modifications to

            
                language for BlitFramebufferNV also apply to BlitFramebuffer:


                (Add to the end of the section describing BlitFramebuffer)


                "If SAMPLE_BUFFERS for the read framebuffer is zero and

            
                SAMPLE_BUFFERS for the draw framebuffer is greater than zero, the

            
                value of the source sample is replicated in each of the destination

            
                samples.


                If SAMPLE_BUFFERS for both the read and draw framebuffers are

            
                greater than zero, and the values of SAMPLES for the read and draw

            
                framebuffers are identical, the samples are copied without

            
                modification from the read framebuffer to the draw framebuffer.

            
                Otherwise, no copy is performed and an INVALID_OPERATION error is

            
                generated."


                (In the error list for BlitFramebuffer, modify the item "An

            
                INVALID_OPERATION error is generated if the draw framebuffer is

            
                multisampled.")


                    * An INVALID_OPERATION error is generated if both the read and

            
                      draw buffers are multisampled, and SAMPLE_BUFFERS for the read and

            
                      draw buffers are not identical.


                (In the error list for BlitFramebuffer, add to the list)


                    * An INVALID_OPERATION error is generated if either the read or draw

            
                      buffer is multisampled, and the formats of the read and draw

            
                      framebuffers are not identical.


            Dependencies on NV_framebuffer_blit


                NV_framebuffer_blit is required.  Technically, NV_framebuffer_blit

            
                would not be required to support multisampled rendering, except for

            
                the fact that it provides the only method of doing a multisample

            
                resovle from a multisample renderbuffer.


            Dependencies on OES_texture_3D and NV_texture_array


                On an OpenGL ES implementation, in the absense of OES_texture_3D or

            
                NV_texture_array, omit references to CopyTexSubImage3DOES and

            
                CopyTexSubImage3DNV, respectively.


            Errors


                The error INVALID_OPERATION is generated if ReadPixels or

            
                CopyTex{Sub}Image* is called while READ_FRAMEBUFFER_BINDING_NV

            
                is non-zero, the read framebuffer is framebuffer complete, and the

            
                value of SAMPLE_BUFFERS for the read framebuffer is greater than

            
                zero.


                If both the draw and read framebuffers are framebuffer complete and

            
                both have a value of SAMPLE_BUFFERS that is greater than zero, then

            
                the error INVALID_OPERATION is generated if BlitFramebufferNV is

            
                called and the values of SAMPLES for the draw and read framebuffers

            
                do not match.


                If both the draw and read framebuffers are framebuffer complete and

            
                either has a value of SAMPLE_BUFFERS that is greater than zero, then

            
                the error INVALID_OPERATION is generated if BlitFramebufferNV is

            
                called and the formats of the draw and read framebuffers are not

            
                identical.


                If either the draw or read framebuffer is framebuffer complete and

            
                has a value of SAMPLE_BUFFERS that is greater than zero, then the

            
                error INVALID_OPERATION is generated if BlitFramebufferNV is called

            
                and the specified source and destination dimensions are not

            
                identical.


                If RenderbufferStorageMultisampleNV is called with <target> not

            
                equal to RENDERBUFFER, the error INVALID_ENUM is generated.


                If RenderbufferStorageMultisampleNV is called with an

            
                <internalformat> that is not listed as one of the color-, depth-

            
                or stencil-renderable formats in Table 4.5, then the error

            
                INVALID_ENUM is generated.


                If RenderbufferStorageMultisampleNV is called with <width> or

            
                <height> greater than MAX_RENDERBUFFER_SIZE, then the error

            
                INVALID_VALUE is generated.


                If RenderbufferStorageMultisampleNV is called with a value of

            
                <samples> that is greater than MAX_SAMPLES_NV or less than zero,

            
                then the error INVALID_VALUE is generated.


                The error OUT_OF_MEMORY is generated when

            
                RenderbufferStorageMultisampleNV cannot create storage of the

            
                specified size.


            New State


                Add to table 6.23 (Renderbuffer State)


                Get Value                        Type    Get Command                 Initial Value  Description             Section

            
                -------------------------------  ------  --------------------------  -------------  --------------------    -------

            
                RENDERBUFFER_SAMPLES_NV          Z+      GetRenderbufferParameteriv  0              number of samples       4.4.3


                Add to table 6.21 (Framebuffer Dependent Values)

            
                the following new framebuffer dependent state.


                Get Value          Type  Get Command     Minimum Value    Description             Section

            
                -----------------  ----  -----------     -------------    -------------------     -------

            
                MAX_SAMPLES_NV     Z+    GetIntegerv     1                Maximum number of       4.4.3

            
                                                                          samples supported

            
                                                                          for multisampling


            Issues


                Issues from EXT_framebuffer_multisample have been removed.


                1) How is this extension different from Halti and ARB_framebuffer_object ?

            
                    - this extension offers the same MSAA functionality as in

            
                      ARB_framebuffer_object

            
                    - it is a superset of Halti in that:

            
                        a) SINGLE-->MSAA and MSAA-->MSAA blits are possible

            
                        b) the blit region may be relocated during the blit


            Revision History

            
                Revision 5, 2015/03/03

            
                  - add interaction with OpenGL ES 3.0 and later

            
                Revision 4, 2012/08/31

            
                  - add interaction with NV_texture_array

            
                Revision 3, 2012/08/29

            
                  - consolidate contributors list

            
                  - be more explicit about the specification version the text is written against

            
                Revision 2, 2012/08/15

            
                  - explicitly state that resolve blits from the window system provided framebuffer

            
                    are possible

            
                  - fix references to table 6.21 and table 6.23

            
                Revision 1, 2012/05/15

            
                  - copied from revision 3 of ANGLE_framebuffer_multisample

            
                  - re-inserted missing functionality of EXT_framebuffer_blit
	Name

	NV_framebuffer_multisample

	Name Strings

	GL_NV_framebuffer_multisample

	Contributors

	Contributors to EXT_framebuffer_multisample
	Contributors from ANGLE_framebuffer_multisample

	Gregory Roth, NVIDIA
	Mathias Heyer, NVIDIA
	Xi Chen, NVIDIA

	Contacts

	Mathias Heyer, NVIDIA (mheyer 'at' nvidia 'dot' com)

	Status

	Complete

	Version

	Last Modified Date: March 03, 2015
	Author Revision: #5

	Number

	OpenGL ES Extension #143

	Dependencies

	Requires OpenGL ES 2.0.

	Requires GL_NV_framebuffer_blit.

	The extension is written against the OpenGL ES 2.0.25
	(November 2, 2010) specification.

	OES_texture_3D affects the definition of this extension.
	NV_texture_array affects the definition of this extension.

	This extension interacts with OpenGL ES 3.0 and later versions.

	Overview

	This extension extends the framebuffer object framework to
	enable multisample rendering.

	The new operation RenderbufferStorageMultisampleNV() allocates
	storage for a renderbuffer object that can be used as a multisample
	buffer. A multisample render buffer image differs from a
	single-sample render buffer image in that a multisample image has a
	number of SAMPLES that is greater than zero. No method is provided
	for creating multisample texture images.

	All of the framebuffer-attachable images attached to a framebuffer
	object must have the same number of SAMPLES or else the framebuffer
	object is not "framebuffer complete". If a framebuffer object with
	multisample attachments is "framebuffer complete", then the
	framebuffer object behaves as if SAMPLE_BUFFERS is one.

	A resolve operation is executed by calling
	BlitFramebufferNV (provided by the NV_framebuffer_blit
	extension) where the source is a multisample framebuffer object
	and the destination is a single-sample framebuffer object.
	Source and destination framebuffer may be either application-created
	or window-system provided.

	New Procedures and Functions

	void RenderbufferStorageMultisampleNV(
	enum target, sizei samples,
	enum internalformat,
	sizei width, sizei height);

	New Tokens

	Accepted by the <pname> parameter of GetRenderbufferParameteriv:

	RENDERBUFFER_SAMPLES_NV 0x8CAB

	Returned by CheckFramebufferStatus:

	FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_NV 0x8D56

	Accepted by the <pname> parameter of GetBooleanv, GetIntegerv,
	and GetFloatv:

	MAX_SAMPLES_NV 0x8D57

	Additions to Chapter 3 of the OpenGL ES 2.0 Specification (Rasterization)

	Add to the last paragraph of 3.7.2 (Alternate Texture Image Specification)
	(as modified by NV_framebuffer_blit) the following:

	"Calling CopyTexSubImage3DOES, CopyTexSubImage3DNV,
	CopyTexImage2D or CopyTexSubImage2D will result in INVALID_OPERATION
	being generated if the object bound to READ_FRAMEBUFFER_BINDING_NV
	is "framebuffer complete" and the value of SAMPLE_BUFFERS is greater
	than zero."

	Additions to Chapter 4 of the OpenGL ES 2.0 Specification (Per-Fragment
	Operations and the Framebuffer)

	Add to 4.3.1 (Reading Pixels), right before the subsection titled
	"Obtaining Pixels from the Framebuffer":

	"ReadPixels generates INVALID_OPERATION if READ_FRAMEBUFFER_BINDING_NV
	(section 4.4) is non-zero, the read framebuffer is framebuffer
	complete, and the value of SAMPLE_BUFFERS for the read framebuffer
	is greater than zero."

	In 4.3.2 (Copying Pixels), add to the section describing BlitFramebufferNV
	that was added by NV_framebuffer_blit.

	"If SAMPLE_BUFFERS for the read framebuffer is greater than zero and
	SAMPLE_BUFFERS for the draw framebuffer is zero, the samples
	corresponding to each pixel location in the source are converted to
	a single sample before being written to the destination.

	If SAMPLE_BUFFERS for the read framebuffer is zero and
	SAMPLE_BUFFERS for the draw framebuffer is greater than zero, the
	value of the source sample is replicated in each of the destination
	samples.

	If SAMPLE_BUFFERS for both the read and draw framebuffers are
	greater than zero, and the values of SAMPLES for the read and draw
	framebuffers are identical, the samples are copied without
	modification from the read framebuffer to the draw framebuffer.
	Otherwise, no copy is performed and an INVALID_OPERATION error is
	generated.

	If SAMPLE_BUFFERS for the read framebuffer is greater than zero and
	the format of the read and draw framebuffers are not identical, no
	copy is performed and an INVALID_OPERATION error is generated.

	Furthermore, if SAMPLE_BUFFERS for either the read framebuffer or
	draw framebuffer is greater than zero, no copy is performed and an
	INVALID_OPERATION error is generated if the dimensions of the source
	and destination rectangles provided to BlitFramebufferNV are not
	identical, or if the formats of the read and draw framebuffers are
	not identical.

	Modification to 4.4.3 (Renderbuffer Objects)

	Add, just above the definition of RenderbufferStorage:

	"The command

	void RenderbufferStorageMultisampleNV(
	enum target, sizei samples,
	enum internalformat,
	sizei width, sizei height);

	establishes the data storage, format, dimensions, and number of
	samples of a renderbuffer object's image. <target> must be
	RENDERBUFFER. <internalformat> must be one of the color-renderable,
	depth-renderable, or stencil-renderable formats described in table 4.5.
	<width> and <height> are the dimensions in pixels of the renderbuffer. If
	either <width> or <height> is greater than the value of
	MAX_RENDERBUFFER_SIZE, or if <samples> is greater than MAX_SAMPLES_NV,
	then the error INVALID_VALUE is generated. If OpenGL ES is unable to
	create a data store of the requested size, the error OUT_OF_MEMORY
	is generated.

	Upon success, RenderbufferStorageMultisampleNV deletes any existing
	data store for the renderbuffer image and the contents of the data
	store after calling RenderbufferStorageMultisampleNV are undefined.
	RENDERBUFFER_WIDTH is set to <width>, RENDERBUFFER_HEIGHT is
	set to <height>, and RENDERBUFFER_INTERNAL_FORMAT is set to
	<internalformat>.

	If <samples> is zero, then RENDERBUFFER_SAMPLES_NV is set to zero.
	Otherwise <samples> represents a request for a desired minimum
	number of samples. Since different implementations may support
	different sample counts for multisampled rendering, the actual
	number of samples allocated for the renderbuffer image is
	implementation dependent. However, the resulting value for
	RENDERBUFFER_SAMPLES_NV is guaranteed to be greater than or equal
	to <samples> and no more than the next larger sample count supported
	by the implementation.

	An OpenGL ES implementation may vary its allocation of internal component
	resolution based on any RenderbufferStorageMultisampleNV parameter (except
	target), but the allocation and chosen internal format must not be a
	function of any other state and cannot be changed once they are
	established. The actual resolution in bits of each component of the
	allocated image can be queried with GetRenderbufferParameteriv."

	Modify the definiton of RenderbufferStorage as follows:

	"The command

	void RenderbufferStorage(enum target, enum internalformat,
	sizei width, sizei height);

	is equivalent to calling RenderbufferStorageMultisampleNV with
	<samples> equal to zero."

	In section 4.4.5 (Framebuffer Completeness) in the subsection
	titled "Framebuffer Completeness" add an entry to the bullet list:

	* The value of RENDERBUFFER_SAMPLES_NV is the same for all attached
	images.
	{ FRAMEBUFFER_INCOMPLETE_MULTISAMPLE_NV }

	Also add a paragraph to the end of the section after the definition
	of CheckFramebufferStatus:

	"The values of SAMPLE_BUFFERS and SAMPLES are derived from the
	attachments of the currently bound framebuffer object. If the
	current DRAW_FRAMEBUFFER_BINDING_NV is not "framebuffer complete",
	then both SAMPLE_BUFFERS and SAMPLES are undefined. Otherwise,
	SAMPLES is equal to the value of RENDERBUFFER_SAMPLES_NV for the
	attached images (which all must have the same value for
	RENDERBUFFER_SAMPLES_NV). Further, SAMPLE_BUFFERS is one if
	SAMPLES is non-zero. Otherwise, SAMPLE_BUFFERS is zero.

	Additions to Chapter 6 of the OpenGL ES 2.0 Specification (State and State
	Requests)

	In section 6.1.3 (Enumeraged Queries), modify the third paragraph
	of the description of GetRenderbufferParameteriv as follows:

	"Upon successful return from GetRenderbufferParameteriv, if
	<pname> is RENDERBUFFER_WIDTH, RENDERBUFFER_HEIGHT,
	RENDERBUFFER_INTERNAL_FORMAT, or RENDERBUFFER_SAMPLES_NV, then <params>
	will contain the width in pixels, height in pixels, internal format, or
	number of samples, respectively, of the image of the renderbuffer
	currently bound to <target>."

	Dependencies on OpenGL ES 3.0 and later

	If OpenGL ES 3.0 or later is supported, the described modifications to
	language for BlitFramebufferNV also apply to BlitFramebuffer:

	(Add to the end of the section describing BlitFramebuffer)

	"If SAMPLE_BUFFERS for the read framebuffer is zero and
	SAMPLE_BUFFERS for the draw framebuffer is greater than zero, the
	value of the source sample is replicated in each of the destination
	samples.

	If SAMPLE_BUFFERS for both the read and draw framebuffers are
	greater than zero, and the values of SAMPLES for the read and draw
	framebuffers are identical, the samples are copied without
	modification from the read framebuffer to the draw framebuffer.
	Otherwise, no copy is performed and an INVALID_OPERATION error is
	generated."

	(In the error list for BlitFramebuffer, modify the item "An
	INVALID_OPERATION error is generated if the draw framebuffer is
	multisampled.")

	* An INVALID_OPERATION error is generated if both the read and
	draw buffers are multisampled, and SAMPLE_BUFFERS for the read and
	draw buffers are not identical.

	(In the error list for BlitFramebuffer, add to the list)

	* An INVALID_OPERATION error is generated if either the read or draw
	buffer is multisampled, and the formats of the read and draw
	framebuffers are not identical.

	Dependencies on NV_framebuffer_blit

	NV_framebuffer_blit is required. Technically, NV_framebuffer_blit
	would not be required to support multisampled rendering, except for
	the fact that it provides the only method of doing a multisample
	resovle from a multisample renderbuffer.

	Dependencies on OES_texture_3D and NV_texture_array

	On an OpenGL ES implementation, in the absense of OES_texture_3D or
	NV_texture_array, omit references to CopyTexSubImage3DOES and
	CopyTexSubImage3DNV, respectively.


	Errors

	The error INVALID_OPERATION is generated if ReadPixels or
	CopyTex{Sub}Image* is called while READ_FRAMEBUFFER_BINDING_NV
	is non-zero, the read framebuffer is framebuffer complete, and the
	value of SAMPLE_BUFFERS for the read framebuffer is greater than
	zero.

	If both the draw and read framebuffers are framebuffer complete and
	both have a value of SAMPLE_BUFFERS that is greater than zero, then
	the error INVALID_OPERATION is generated if BlitFramebufferNV is
	called and the values of SAMPLES for the draw and read framebuffers
	do not match.

	If both the draw and read framebuffers are framebuffer complete and
	either has a value of SAMPLE_BUFFERS that is greater than zero, then
	the error INVALID_OPERATION is generated if BlitFramebufferNV is
	called and the formats of the draw and read framebuffers are not
	identical.

	If either the draw or read framebuffer is framebuffer complete and
	has a value of SAMPLE_BUFFERS that is greater than zero, then the
	error INVALID_OPERATION is generated if BlitFramebufferNV is called
	and the specified source and destination dimensions are not
	identical.

	If RenderbufferStorageMultisampleNV is called with <target> not
	equal to RENDERBUFFER, the error INVALID_ENUM is generated.

	If RenderbufferStorageMultisampleNV is called with an
	<internalformat> that is not listed as one of the color-, depth-
	or stencil-renderable formats in Table 4.5, then the error
	INVALID_ENUM is generated.

	If RenderbufferStorageMultisampleNV is called with <width> or
	<height> greater than MAX_RENDERBUFFER_SIZE, then the error
	INVALID_VALUE is generated.

	If RenderbufferStorageMultisampleNV is called with a value of
	<samples> that is greater than MAX_SAMPLES_NV or less than zero,
	then the error INVALID_VALUE is generated.

	The error OUT_OF_MEMORY is generated when
	RenderbufferStorageMultisampleNV cannot create storage of the
	specified size.

	New State

	Add to table 6.23 (Renderbuffer State)

	Get Value Type Get Command Initial Value Description Section
	------------------------------- ------ -------------------------- ------------- -------------------- -------
	RENDERBUFFER_SAMPLES_NV Z+ GetRenderbufferParameteriv 0 number of samples 4.4.3


	Add to table 6.21 (Framebuffer Dependent Values)
	the following new framebuffer dependent state.

	Get Value Type Get Command Minimum Value Description Section
	----------------- ---- ----------- ------------- ------------------- -------
	MAX_SAMPLES_NV Z+ GetIntegerv 1 Maximum number of 4.4.3
	samples supported
	for multisampling



	Issues

	Issues from EXT_framebuffer_multisample have been removed.

	1) How is this extension different from Halti and ARB_framebuffer_object ?
	- this extension offers the same MSAA functionality as in
	ARB_framebuffer_object
	- it is a superset of Halti in that:
	a) SINGLE-->MSAA and MSAA-->MSAA blits are possible
	b) the blit region may be relocated during the blit

	Revision History
	Revision 5, 2015/03/03
	- add interaction with OpenGL ES 3.0 and later
	Revision 4, 2012/08/31
	- add interaction with NV_texture_array
	Revision 3, 2012/08/29
	- consolidate contributors list
	- be more explicit about the specification version the text is written against
	Revision 2, 2012/08/15
	- explicitly state that resolve blits from the window system provided framebuffer
	are possible
	- fix references to table 6.21 and table 6.23
	Revision 1, 2012/05/15
	- copied from revision 3 of ANGLE_framebuffer_multisample
	- re-inserted missing functionality of EXT_framebuffer_blit